How do I model this type of shape?
Here are 2 ways to do it:

Create a UV Sphere of 30 segments and 10 rings, keep only 1/10:



Mirror it:



Array it with an empty as Object Offset that you rotate 72°:



Cut the hole, squeeze on the Z axis, change the topology:


Or:

Create a 5 vertex cylinder, delete 4 of the faces, rebuild it with an Array modifier/Object Offset mode with an empty that you rotate 72° on the Z axis:



Subdivide it a bit, cut the hole:



Swell the shape with a Cast modifier:


From now on I guess you can continue in many ways (subdivide, sculpt...).